Question

我正在尝试从bmp文件中提取RGB分量，但是当到达Data[i][j].Blue时出现段错误。我尝试打印出三种颜色的十六进制，并很好地打印出它们，但随后打印出，所有RGB分量均为0xFF，然后当它变成蓝色时就会出现故障。我得到的任何帮助都将不胜感激。

int inputColors(char *filename, struct INFOHEADER *InfoHeader, struct PIXEL **Data){
    int i = 0, j = 0;
    FILE *inputFile;

    printf("The height of the picture is %d\n", InfoHeader->Height);
    printf("The width of the picture is %d\n", InfoHeader->Width);

    if((inputFile = fopen(filename, "r")) == NULL){
            printf("Unable to open .bmp file\n");
            exit(1);
    }

    //Mallocing enough space for the 2D structures of pixels (colors)
    Data = (struct PIXEL **)malloc(InfoHeader->Width * sizeof(struct PIXEL *));
    for(i = 0; i < InfoHeader->Height; i++){
            Data[i] = (struct PIXEL *)malloc(InfoHeader->Height * InfoHeader->Width * sizeof(struct PIXEL));
    }

    //This goes until after we are down with the header
    fseek(inputFile, 54, SEEK_SET);

    //Inputing the data into the malloced struct
    i = 0;
    for(i = 0; i < InfoHeader->Height; i++){
            for(j = 0; j < InfoHeader->Width; j++){
                    Data[i][j].Red = getc(inputFile);
            //      printf("The Red componet is %X\n", Data[i][j].Red);
                    Data[i][j].Green = getc(inputFile);
            //      printf("The green componet is %X\n", Data[i][j].Green);
                    Data[i][j].Blue = getc(inputFile);
            //      printf("The blue componet is %X\n", Data[i][j].Blue);
            }
    }

    fclose(inputFile);
return 0;
}

Answer 1

对于初学者来说，您的第一个malloc使用

InfoHeader->Width * sizeof(struct PIXEL *)

但是，当您遍历数组时，可以使用InfoHeader-> Height。由于这种不匹配，如果InfoHeader-> Width小于InfoHeader-> Height，它将不会分配足够的内存来执行迭代，并且将执行SEGFAULT。

Answer 2

Data = (struct PIXEL **)malloc(InfoHeader->Width * sizeof(struct PIXEL *));
//                                         ^^^^^
for(i = 0; i < InfoHeader->Height; i++){
//                         ^^^^^^
        Data[i] = (struct PIXEL *)malloc(InfoHeader->Height * InfoHeader->Width * sizeof(struct PIXEL));
}

尝试从bmp文件中提取RGB分量时，为什么我的代码段出错？

2 个答案: